Denitrification performance of non-pitch coal-based activated coke by the introduction of MnO –CeO –M (FeO , CoO ) at low temperature

Effect of pre-oxidation process on V2O5/AC catalyst for the selective catalytic reduction of NOx with NH3

Activated coke-based catalysts have attracted extensive attention in denitration by selective catalytic reduction by NH₃ (NH₃-SCR), due to their excellent catalytic performance at low temperature. In the paper, the V₂O₅/AC catalyst was prepared by the impregnation method to investigate the effect of pre-oxidation process on its NH₃-SCR activity. Activity test results show that the V₂O₅/AC catalyst with 4-h pre-oxidation exhibits the best NO_x removal efficiency, which reaches the NO_x conversion is over 75% in the range of 200-240 °C and exhibits an excellent resistance to SO₂ and H₂O. Characterization results demonstrate that the V⁴⁺ was oxidized by oxygen molecule during pre-oxidation process, which contributes to the formation of V⁵⁺ ions and surface-active oxygen species. The surface-active oxygen species are conducive to promoting the "fast SCR" reaction; thus, the pre-oxidized process can contribute to the superior NH₃-SCR performance for V₂O₅/AC catalyst at low temperature.

Recent progress of low-temperature selective catalytic reduction of NOx with NH3 over manganese oxide-based catalysts

Selective catalytic reduction with NH3 (NH3−SCR) was the most efficient approach to mitigate the emission of nitrogen oxides (NOx). Although the conventional manganese oxide-based catalyst had gradually become a kind...

Pilot test of environment-friendly catalysts for the DeNOx of low-temperature flue gas from a coal-fired plant

This figure reflects the process flow diagram of low-temperature SCR DeNO_x and the test efficiency of 3400 h.

Significantly enhanced Pb resistance of a Co-modified Mn–Ce–Ox/TiO2 catalyst for low-temperature NH3-SCR of NOx

Co modification can significantly improve the performance for low-temperature NH₃-SCR of NO_x and the Pb resistance of the Mn–Ce–O_x/TiO₂ catalyst.

Tunable preparation of highly dispersed Ni x Mn-LDO catalysts derived from Ni x Mn-LDHs precursors and application in low-temperature NH3-SCR reactions

A series of Ni x Mn bimixed metal oxides (Ni x Mn-LDO) were prepared via calcining Ni x Mn layered double hydroxides (Ni x Mn-LDHs) precursors at 400 °C and applied as catalysts in the selective catalytic reduction (SCR) of NO x with NH3. The DeNO x performance of catalysts was optimized by adjusting the Ni/Mn molar ratios of Ni x Mn-LDO precursors, in which Ni5Mn-LDO exhibited above 90% NO x conversion and N2 selectivity at a temperature zone of 180-360 °C. Besides, Ni5Mn-LDO possessed considerable SO2 & H2O resistance and outstanding stability. Multiple characterization techniques were used to analyze the physicochemical properties of the catalysts. The analysis results indicated that all catalysts had the same active species Ni6MnO8, while their particle sizes showed significant differences. Notably, the uniform distribution of active species particles in the Ni5Mn-LDO catalyst provided the rich surface acidity and suitable redox ability which were the primary causes for its desirable DeNO x property.

Study on the denitrification performance of FexLayOz/activated coke for NH3-SCR and the effect of CO escaped from activated coke at mid-high temperature on catalytic activity

Currently, activated coke is widely used in the removal of multiple pollutants from industrial flue gas. In this paper, a series of novel Fe_xLa_yO_z/AC catalysts was prepared by the incipient wetness impregnation for NH₃-SCR denitrification reaction. The introduction of Fe-La bimetal oxides significantly improved the denitrification performance of activated coke at mid-high temperature, and 4% Fe_0.3La_0.7O_1.5/AC exhibited a superior NO_x conversion efficiency of 90.1% at 400 °C. The catalysts were further characterized by BET, SEM, XRD, Raman, EPR, XPS, FTIR, NH₃-TPD, H₂-TPR, et al., whose results showed that the perovskite-type oxide of LaFeO₃ and oxygen vacancies were produced on the catalysts' surfaces during roasting. Fe-La doping enhanced the amount of acid sites (mainly Lewis and other stronger acid sites) and the content of multifarious oxygen species, which were beneficial for NO_x removal at mid-high temperature. Moreover, it was investigated that the effect of released CO from activated coke at mid-high temperature on the NO_x removal through the lifetime test, in which it was found that a large amount of CO produced by pyrolysis of activated coke could promote the NO_x removal, and long-term escaping of CO on the activated coke carrier did not have a significant negative impact on catalytic performance. The results of the TG-IR test showed that volatile matter is released from the activated coke while TG results showed that the weight loss rate of 4% Fe_0.3La_0.7O_1.5/AC only was 0.0015~0.007%/min at 300-400 °C. Hence, 4% Fe_0.3La_0.7O_1.5/AC had excellent thermal stability and denitrification performance to be continuously used at mid-high temperature. Finally, the mechanisms were proposed on the basis of experiments and characterization results.

A Review of Low Temperature NH3-SCR for Removal of NOx

The importance of the low-temperature selective catalytic reduction (LT-SCR) of NOx by NH3 is increasing due to the recent severe pollution regulations being imposed around the world. Supported and mixed transition metal oxides have been widely investigated for LT-SCR technology. However, these catalytic materials have some drawbacks, especially in terms of catalyst poisoning by H2O or/and SO2. Hence, the development of catalysts for the LT-SCR process is still under active investigation throughout seeking better performance. Extensive research efforts have been made to develop new advanced materials for this technology. This article critically reviews the recent research progress on supported transition and mixed transition metal oxide catalysts for the LT-SCR reaction. The review covered the description of the influence of operating conditions and promoters on the LT-SCR performance. The reaction mechanism, reaction intermediates, and active sites are also discussed in detail using isotopic labelling and in situ FT-IR studies.